title: Intraoperative neuromonitoring with MEPs and prediction of postoperative neurological deficits in patients undergoing surgery for cervical and cervicothoracic myelopathy.
abstract: OBJECTIVE
  The use of intraoperative neurophysiological monitoring (IONM) in surgical decompression surgery for myelopathy may assist the surgeon in taking corrective measures to reduce or prevent permanent neurological deficits. We evaluated the efficacy of IONM in cervical and cervicothoracic spondylotic myelopathy (CSM) cases.
  
  
  METHODS
  The authors retrospectively reviewed 140 cases involving patients who underwent surgery for CSM utilizing IONM during 2011 at the University of California, San Francisco. Data on preoperative clinical variables, intraoperative changes in transcranial motor evoked potentials (MEPs), and postoperative new neurological deficits were collected. Associations between categorical variables were analyzed with the Fisher exact test.
  
  
  RESULTS
  Of the 140 patients, 16 (11%) had significant intraoperative decreases in MEPs. In 8 of these cases, the MEP signal did not return to baseline values by the end of the operation. There were 8 (6%) postoperative deficits, of which 6 were C-5 palsies and 2 were paraparesis. Six of the patients with postoperative deficits had demonstrated persistent MEP signal change on IONM. There was a significant association between persistent MEP changes and postoperative deficits (p < 0.001). The sensitivity of intraoperative MEP monitoring was 75%, the specificity 98%, the positive predictive value 75%, and the negative predictive value 98%. Due to higher rates of false negatives, the sensitivity decreased to 60% in the subgroup of patients with vascular disease comorbidity. The sensitivity increased to 100% in elderly patients and in patients with preoperative motor deficits. The sensitivity and positive predictive value of deltoid and biceps MEP changes in predicting C-5 palsy were 67% and 67%, respectively.
  
  
  CONCLUSIONS
  The authors found a correlation between decreased intraoperative MEPs and postoperative new neurological deficits in patients with CSM. Sensitivity varies based on patient comorbidities, age, and preoperative neurological function. Monitoring of MEPs is a useful adjunct for CSM cases, and the authors have developed a checklist to standardize their responses to intraoperative MEP changes.
authors.affiliation: Department of Neurological Surgery, University of California, San Francisco, California 94143-0112, USA.
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Clark
authors.forename: John E
authors.initials: JE
authors.lastname: Ziewacz
authors.forename: Michael
authors.initials: M
authors.lastname: Safaee
authors.forename: Darryl
authors.initials: D
authors.lastname: Lau
authors.forename: Russ
authors.initials: R
authors.lastname: Lyon
authors.forename: Dean
authors.initials: D
authors.lastname: Chou
authors.forename: Philip R
authors.initials: PR
authors.lastname: Weinstein
authors.forename: Christopher P
authors.initials: CP
authors.lastname: Ames
authors.forename: John P
authors.initials: JP
authors.lastname: Clark
authors.forename: Praveen V
authors.initials: PV
authors.lastname: Mummaneni
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002574:Cervical Vertebrae / Q000473:pathology / Q000601:surgery; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative / Q000379:methods*; D009422:Nervous System Diseases / Q000175:diagnosis / Q000503:physiopathology*; D011183:Postoperative Complications / Q000175:diagnosis / Q000503:physiopathology*; D011237:Predictive Value of Tests; D012189:Retrospective Studies; D013118:Spinal Cord Diseases / Q000175:diagnosis / Q000503:physiopathology* / Q000601:surgery; D013904:Thoracic Vertebrae / Q000473:pathology / Q000601:surgery